Serial I/O Pin Descriptions; Table 7-4. Dsp1611/17/18/27/28/29 Serial I/O Pins - Lucent Technologies DSP1617 Information Manual

DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
Serial I/O

7.3 Serial I/O Pin Descriptions

The physical serial I/O port consists of 12 signals: four are used for serial input, five are used for serial output, and
three are used in multiprocessor applications, TDM applications, or both.
and description.

Table 7-4. DSP1611/17/18/27/28/29 Serial I/O Pins

Symbol Type
DI I Data Input. Serial data latched on the rising edge of ICK, either LSB or MSB first corre-
sponding to the sioc register MSB field.
†
ICK I/O Input Clock. Clock for serial input data. Corresponding to the sioc register ICK field in
active mode, ICK is an output; otherwise in passive mode, ICK is an input.
†
Input Load. Falling edge of ILD indicates the beginning of a serial input word. Correspond-
ILD I/O
ing to the sioc register ICK field in active mode, ILD is an output; otherwise in passive mode,
ILD is an input.
†
IBF O Input Buffer Full. IBF is asserted if the input buffer is filled and negated by a read of the
buffer. IBF is also negated by asserting RSTB.
†
DO O Data Output. Serial data output from the output shift register (osr), either LSB or MSB first,
corresponding to the sioc register MSB field. DO changes on the rising edges of OCK for
the DSP1611/17/18. For the DSP1627/28/29, DO changes on the rising or falling edge of
OCK corresponding to the DODLY bit in the sioc register. DO is 3-stated if DOEN is high.
†
DOEN I/O Data Output Enable (Active-Low). An input if not in the multiprocessor mode. DO and
SADD are enabled only if DOEN is low. In the multiprocessor mode (tdms register MODE
field set), DOEN indicates a valid time slot for a serial output and is bidirectional.
†
OCK I/O Output Clock. Clock for serial output data. Corresponding to the sioc register OCK field in
active mode, OCK is an output; otherwise in passive mode, OCK is an input.
†
OLD I/O Output Load. Clock for loading the output shift register (osr) from the output buffer
(sdx[out]). A falling edge of OLD indicates the beginning of a serial output word. Corre-
sponding to the sioc register OLD field in active mode, OLD is an output; otherwise in pas-
sive, OLD is an input.
†
Output Buffer Empty. OBE is asserted if the output buffer is emptied (moved to the output
OBE O
shift register for transmission). It is cleared with a write to the buffer (sdx). OBE is also set
by asserting RSTB.
†
Serial Address (Active-Low). A 16-bit serial bit stream typically used for addressing during
SADD I/O
multiprocessor communication between multiple DSP devices. In multiprocessor mode,
SADD is an output if the tdms time slot dictates a serial transmission; otherwise, it is an
input. Both the source and destination DSP are identified in the transmission. SADD is
always an output when not in multiprocessor mode and can be used as a second 16-bit serial
output. SADD is 3-stated if DOEN is high and must be tied high through a resistor when
used in multiprocessor applications.
†
SYNC I/O Multiprocessor Synchronization. Typically used in the multiprocessor mode. A falling
edge of SYNC indicates the first word of a TDM I/O stream and causes the synchronization
of the active ILD and OLD generators. SYNC is an output if the tdms register SYNC field is
set; otherwise, it is an input. SYNC must be tied low if it is not used as an output. If used as
an output, SYNC = ILD/OLD ÷ 8 or 16 corresponding to the setting of the SYNCSP field of
the tdms register. This procedure can be used to generate a slow clock for SIO operation.
† 3-stated.
7-12
Name/Description
DRAFT COPY
Information Manual
Table 7-4 lists each signal with its type
Lucent Technologies Inc.
April 1998